1. Field of the Invention
Example embodiments of the present invention relates generally to an image sensor device and methods thereof, and more particularly to an image sensor device including at least one microlens and methods thereof.
2. Description of the Related Art
Image sensor modules may include solid state image sensing devices or complementary metal oxide semiconductor (CMOS) image sensors (CISs). Image sensor modules may detect an image of an object and output corresponding electrical signals using photoelectric conversion devices and/or charge coupled devices (CCDs). Image sensor modules may be utilized in a wide range of applications including, for example, digital cameras, digital camcorders, telecommunication terminals, camera phones, multi-media personal computers and surveillance cameras.
FIG. 1 is a cross-sectional view of a conventional image sensor module 70. Referring to FIG. 1, the conventional image sensor module 70 may include a flexible circuit substrate 71 and an image sensor device 40 mounted on an upper surface of the flexible circuit substrate 71. The image sensor device 40 may include an image sensor chip 22 having chip pads 25 and microlenses 27. A protective plate 32 may be attached to the image sensor chip 22 with a photosensitive adhesive pattern 36. The protective plate 32 may include through holes 37, through which the chip pads 25 of the image sensor chip 22 may be exposed. Bonding wires 76 may electrically connect the flexible circuit substrate 71 to the chip pads 25 of the image sensor chip 22. A lens unit 77 may be formed on the upper surface of the flexible circuit substrate 71 at least partially surrounding (e.g., fully surrounding) the image sensor device 40 and may include a lens 78 for focusing an image on the image sensor device 40 and/or protecting the image sensor device 40.
The protective plate 32 may protect the microlenses 27 of the image sensor chip 22 at a wafer level, which may reduce contamination of the microlenses 27 due to fine particles present in a manufacturing environment of the image sensor module 70.
FIGS. 2 through 9 are cross-sectional views of a manufacturing process for the image sensor device 40 of FIG. 1.
Referring to FIG. 2, a wafer 20 may be formed having a silicon substrate 21 and a plurality of image sensor chips 22 mounted on the silicon substrate 21. Scribe lines 24 may be formed between adjacent image sensor chips 22. Each of the plurality of image sensor chips 22 may have a plurality of chip pads 25 formed in a peripheral region of an active surface 23 and a color filter 28 formed at a central region of the active surface 23. Each of the plurality of image sensor chips 22 may further include an area 26 of the active surface (hereinafter referred to as one of an adhesive region, an attachment region, a bonding region and/or an intermediate region) between the peripheral region and the central region. A planarization layer 29 may be formed on the active surface 23 to cover the chip pads 25 and the color filter 28. Microlenses 27 may be arranged on the planarization layer 29 and indirectly on the color filter 28.
Referring to FIG. 3, a photosensitive pattern 38 may be formed to cover the microlenses 27. The photosensitive pattern 38 may include an opening 39 through which a portion of the planarization layer 29 on the chip pads 25 may be exposed. Referring to FIG. 4, the exposed portion of the planarization layer 29 may be removed to expose the chip pads 25. Referring to FIG. 5, the photosensitive pattern 38 may be removed with a removal process.
Referring to FIG. 6, a liquid photosensitive adhesive may be applied to the active surface 23 and may be rotated to form a photosensitive adhesive layer 35, for example having a uniform thickness. Referring to FIG. 7, the photosensitive adhesive layer 35 may be exposed and developed to form a photosensitive adhesive pattern 36. The photosensitive adhesive layer 35 may be removed using a conventional photolithography process. The conventional photolithography process may leave a portion of the photosensitive adhesive layer 35 (e.g., an adhesive residue) in the adhesive region 26. The photosensitive adhesive pattern 36 may thereby be formed as a square dam surrounding the microlenses 27. The height of the photosensitive adhesive pattern 36 may be greater than or equal to that of the microlenses 27.
Referring to FIG. 8, a protective plate 30 may be attached to the photosensitive adhesive pattern 36. The protective plate 30 may be aligned with the wafer 20, such that the chip pads 25 of the image sensor chip 22 may correspond to the through holes 37 of the protective plate 30.
Referring to FIG. 9, the wafer 20 having the protective plate 30 may be sawn along the scribe lines 24 with a sawing device 60. The wafer 20 may be separated by the sawing into a plurality of image sensor chips 22 each having a corresponding protective plate 32.
Referring again to FIG. 7, during the formation of the photosensitive adhesive layer 35, a residue 35a of the photosensitive adhesive layer 35 may remain on the active surface 23 and/or on the microlenses 27 after the above-described photolithography removal process. Since the microlenses 27 may each have a hemispheric shape and a curved surface, it may be difficult to spread a developing layer or solution to corners of the microlenses 27. Thus, the photosensitive adhesive layer 35 may not be completely removed.
The residue 35a may be cured during attachment of the protective plate 30 as illustrated in FIG. 8 and may thereafter remain on the microlenses 27, for example as a thin film or particles. The residue 35a may contaminate, damage and/or otherwise impair a functionality of the microlenses 27.
The image sensor module 70 of FIG. 1, including the microlenses 27 with the residue 35a as illustrated in FIGS. 7 and 8 may not function properly due at least in part to the residue 35a. For example, a contaminated portion (e.g., the residue 35a) of at least one of the microlenses 27 may scatter incident light which may be received at the microlenses 27 after the photolithography removal process. A likelihood that light energy from the received incident light may be transferred to a photodiode below the microlenses 27 may thereby be reduced, which may degrade the performance of the image sensor device 40 of the image sensor module 70.